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ELK consequence-based reasoning engine
There is a newer version: 0.4.3
/*
 * #%L
 * elk-reasoner
 * 
 * $Id$
 * $HeadURL$
 * %%
 * Copyright (C) 2011 Oxford University Computing Laboratory
 * %%
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 * 
 *      http://www.apache.org/licenses/LICENSE-2.0
 * 
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 * #L%
 */
/**
 * @author Yevgeny Kazakov, May 15, 2011
 */
package org.semanticweb.elk.reasoner.taxonomy;

import java.util.AbstractSet;
import java.util.ArrayList;
import java.util.Collection;
import java.util.Collections;
import java.util.Iterator;
import java.util.LinkedList;
import java.util.List;
import java.util.Queue;
import java.util.Set;
import java.util.concurrent.atomic.AtomicBoolean;

import org.apache.log4j.Logger;
import org.semanticweb.elk.owl.interfaces.ElkClass;
import org.semanticweb.elk.owl.interfaces.ElkNamedIndividual;
import org.semanticweb.elk.owl.util.Comparators;
import org.semanticweb.elk.reasoner.taxonomy.model.UpdateableInstanceNode;
import org.semanticweb.elk.reasoner.taxonomy.model.UpdateableTypeNode;
import org.semanticweb.elk.util.collections.ArrayHashSet;
import org.semanticweb.elk.util.hashing.HashGenerator;

/**
 * Class for storing information about a class in the context of classification.
 * It is the main data container for {@link IndividualClassTaxonomy} objects.
 * Like most such data containers in ELK, it is read-only for public access but
 * provides package-private ways of modifying it. Modifications of this class
 * happen in implementations of {@link IndividualClassTaxonomy} only.
 * 
 * @author Yevgeny Kazakov
 * @author Markus Kroetzsch
 */
public class IndividualNode implements
		UpdateableInstanceNode {

	// logger for events
	private static final Logger LOGGER_ = Logger
			.getLogger(IndividualNode.class);

	/**
	 * Equivalent ElkClass objects that are representatives of this node.
	 */
	private final List members_;
	/**
	 * ElkClass nodes whose members are direct types of the members of this
	 * node.
	 */
	private final Set> directTypeNodes_;
	/**
	 * true if the direct type nodes need to be recomputed
	 */
	private final AtomicBoolean modified_ = new AtomicBoolean(true);
	

	/**
	 * Constructing the class node for a given taxonomy and the set of
	 * equivalent classes.
	 * 
	 * @param taxonomy
	 *            the taxonomy to which this node belongs
	 * @param members
	 *            non-empty list of equivalent ElkClass objects
	 */
	protected IndividualNode(Collection members) {

		this.members_ = new ArrayList(members);
		this.directTypeNodes_ = new ArrayHashSet>();
		Collections.sort(this.members_,
				Comparators.ELK_NAMED_INDIVIDUAL_COMPARATOR);
	}

	/**
	 * Add a direct super-class node. This method is not thread safe.
	 * 
	 * @param typeNode
	 *            node to add
	 */
	@Override
	public void addDirectTypeNode(UpdateableTypeNode typeNode) {
		if (LOGGER_.isTraceEnabled())
			LOGGER_.trace(this + ": new direct type-node " + typeNode);
		directTypeNodes_.add(typeNode);
	}

	@Override
	public Set getMembers() {
		// create an unmodifiable set view of the members; alternatively, one
		// could have created a TreeSet, but it consumes more memory
		return new AbstractSet() {

			@Override
			public boolean contains(Object arg) {
				if (arg instanceof ElkNamedIndividual)
					return (Collections.binarySearch(members_,
							(ElkNamedIndividual) arg,
							Comparators.ELK_NAMED_INDIVIDUAL_COMPARATOR) >= 0);
				return false;
			}

			@Override
			public boolean isEmpty() {
				return members_.isEmpty();
			}

			@Override
			public Iterator iterator() {
				return members_.iterator();
			}

			@Override
			public int size() {
				return members_.size();
			}

		};
	}
	
	public void setMembers(Collection members) {
		if (LOGGER_.isTraceEnabled())
			LOGGER_.trace(this + ": updating members to " + members);
		members_.clear();
		members_.addAll(members);
		Collections.sort(this.members_, Comparators.ELK_NAMED_INDIVIDUAL_COMPARATOR);
	}

	@Override
	public ElkNamedIndividual getCanonicalMember() {
		return members_.get(0);
	}

	@Override
	public Set> getDirectTypeNodes() {
		return Collections.unmodifiableSet(directTypeNodes_);
	}

	@Override
	public Set> getAllTypeNodes() {
		Set> result = new ArrayHashSet>(
				directTypeNodes_.size());

		Queue> todo = new LinkedList>();

		todo.addAll(directTypeNodes_);

		while (!todo.isEmpty()) {
			UpdateableTypeNode next = todo.poll();

			if (result.add(next)) {
				for (UpdateableTypeNode nextSuperNode : next
						.getDirectUpdateableSuperNodes())
					todo.add(nextSuperNode);
			}
		}

		return Collections.unmodifiableSet(result);
	}

	private final int hashCode_ = HashGenerator.generateNextHashCode();

	@Override
	public final int hashCode() {
		return hashCode_;
	}

	@Override
	public String toString() {
		return getCanonicalMember().getIri().getFullIriAsString();
	}

	@Override
	public boolean trySetModified(boolean modified) {
		boolean result = modified_.compareAndSet(!modified, modified);
		
		if (result && LOGGER_.isTraceEnabled()) {
			LOGGER_.trace("node " + this + ": set "
					+ (modified ? "modified" : "not modifiled"));
		}
		
		return result;
	}

	@Override
	public boolean isModified() {
		return modified_.get();
	}


	@Override
	public void removeDirectTypeNode(
			UpdateableTypeNode typeNode) {
		if (LOGGER_.isTraceEnabled()) {
			LOGGER_.trace(this + ": removing direct type node: " + typeNode);
		}
		
		directTypeNodes_.remove(typeNode);
	}
}